Near-Fatal, Delayed Diagnosis of Kingella kingae Endocarditis in an Infant.

We report a case of a 15-month-old male patient who presented with a two-week history of fever, lethargy, and mild respiratory symptoms. Initial investigations showed markedly elevated inflammatory markers, and chest imaging was interpreted as pneumonia. The patient was discharged on oral amoxicillin. Blood cultures later identified Kingella kingae (K. kingae), but no change in antibiotic therapy or follow-up was initiated due to apparent clinical improvement. Thirteen days later, the patient was readmitted in septic condition with a large mitral valve vegetation. He developed cardiac arrest during anesthesia induction and underwent emergent mitral valve reconstruction. Postoperative neuroimaging revealed multiple infarctions in the left middle cerebral artery territory. The patient is recovering with right-sided hemiparesis and continues to receive multidisciplinary rehabilitation and cardiologic follow-up. This case underscores the importance of considering infective endocarditis in pediatric patients with K. kingae bacteremia, a rare organism with limited literature on its clinical spectrum, even in the absence of classic features. Early echocardiographic assessment is critical to reduce the risk of severe complications.